In organic chemistry, the ketone functional group is usually represented as what type of structure?

The ketone functional group is represented as R-CO-R', where R and R' are hydrocarbon chains or groups of atoms. This structure highlights that a ketone contains a carbonyl group (C=O) bonded to two carbon atoms, which can be the same or different.

The carbonyl carbon (the carbon atom within the C=O group) is flanked by two hydrocarbon groups, indicating that ketones are found where the carbonyl is situated between two alkyl groups (or aryl groups). This is a distinguishing characteristic of ketones as compared to other organic functional groups.

The choice of R-CO-R' accurately illustrates this configuration, encapsulating the essence of what defines a ketone in organic chemistry. The other answer choices represent different functional groups: R-OH denotes an alcohol, R-CHO depicts an aldehyde, and R-COOH signifies a carboxylic acid, each with their own distinct structures and properties.